well. I have a small, well hopefully small problem. I have a 94 Z with a recently acquired EXTREME overheating problem. Upon very recently It lets me drive it for 10 minutes and its already hitting around 260 degrees. This car has NEVER had ANY problem like this. It's heating has been off ever since i put my new distributor on and had to take the water pump off really. But now it's much worse. I've noticed a low pitched grinding, but i was told it was my alternator not my water pump. and i've heard it LONG before any heat issues. Yesterday i checked my thermostat, and today i cleaned out the radiator bu letting a hose run through the system for about a half hour (to get all the rusty colored water out). It helped a small bit barely though. And now if i idle for 2 seconds it shoots up to red. I just bought a new radiator cap, and a temp sensor. What now?? Any help would be greatly appreciated!!

 

I don't know about the grinding but, it sounds like you may have air pockets in your coolant system. I had this same problem and it took me forever to figure out. follow this guide and it will for sure get the air out. http://shbox.com/1/4th_gen_tech2.html#radflush

 

I would put my money on when you flushed the system you didnt bleed the air out. One of those Lt1 things you have to learn the hard way sometimes, hopefully without replacing a head gasket. 260 is pretty hot

 

x2 on the bleeding.

 

If your car is reaching that temp. in a few seconds, it could be a faulty gauge.

Are your fans working? Did you bleed the system? You said you checked your thermostat. How did you test it? Sounds like your thermostat is stuck shut to me. Even if your fans weren't working and there was air in the system, it wouldn't get that hot, that quickly.

Replace the thermostat and report back the results.

 

I disagree. You can watch the temp needle climb if the system has air in it...it'll go right to the red. While you might be right about the thermostat, I'd recommend bleeding the system first. It's free and, in my opinion, a valid possible cause for the problem.

 

I've had air in my system more than a few times and have never had my car reach 260 within seconds, so I'm speaking from my personal experience. I would be very surprised to find out that his problem is solely air in the system, but I could be wrong.

 

Recheck the coolant level in the radiator, not the overflow.

 

well for bleeding the system guys, i think i went wrong when i completely took out the screw on the hose connected to the thermostat when i was filling the radiator up. Water came out of the hole and i put the screw back in at that time. Are there more screws that i have to bleed??? I know the gauge isn't faulty because i maxed it out ONE time last week on the highway driving my girlfriend to work. water shot all out the side of my car from the COOLANT pipe. I sat in her work parking lot for 2 hours letting the P.O.S. cool down. I was worried i did damage but none that i can physically see on the outer half of the block was done. Another thing that was strange to me was i ran the water for 30 minutes until EVERYTHING was clean water. I drove the car came home, opened the R-Cap and the water was rusty looking again. It will usually take the car 12 or so minutes to go all the way to the top of the red. When the water shot out last week, it was passed the red. I didn't think anything of it because i DID think my gauge was busted. Turns out it's not. Now..... my fans. haha........ they come on once in a while. they came on today for me and the car seemed to almost heat up. When my dad checked the fans one came on fast at the passenger side fan came on at a much slower speed. BY THE WAY ALL 3 RELAYS WORK FINE!

 

Did you remove the air dam from the front underbody of the car?

 

There are 2 screws for bleeding air out of the system. After you've filled the system, start the car, and with the car running, then open (don't remove, just crack open) those screws to vent the air. Most likely you still have air pockets you haven't gotten out.

Verify both screws are bleed.

There are also 2 temp sensors; one for the gauge, and one for the PCM; they ARE different and one of those maybe bad.

 

Air dam is still there. and could you maybe point me to the other screw. I also noticed when i was driving the Temp gauge fluctuated a little bit up and down. is this caused by air in the line?? i really love this car and i just wanna get it fixed lol

 

wow i didnt know that there were two. i replaced the temp sensor that sits on the drivers side about an inch below the water pump

 

That isn't a sending unit, that runs to the ECU to determine fuel delivery at cold and warm temps.

 

so i need a different part. alright. Well i just turned the car on opened BOTH of the bleeders i revved the engine and a couple drops of water leaked out of both. I let it run for about 2 minutes. Hopefully that helped. So i'm guessing that is my problem, the sending unit, well if the air isn't the problem anyway. So where does this sending unit sit. Because i didn't even know about the thing. (Not good) Thanks so much for the help all you guys are giving me by the way. I REALLY don't want to blow up a motor sent from Jesus Christ